Hall Effect Position Sensors Information

Hall effect position sensors are noncontact devices that convert energy from a magnetic field into an electrical signal.

How Hall Effect Position Sensors Work

The sensors use the Hall effect, an electrical potential (the Hall voltage) that is developed between the two edges of a current-carrying conductor whose faces are perpendicular to an applied current flow. The Hall element is the most basic magnetic field sensor. This video reviews the Hall effect:

Video Credit: Sensorlytics

This video demonstrates a Hall effect sensor interacting to various magnets:

Video Credit: KJ Magnetics Products

Types of Hall Effect Position Sensors

Hall effect position sensors differ in terms of body style. Barrel devices are cylindrical and typically threaded. Limit-switch sensors are similar in appearance to a contact limit switch. Rectangular/block devices are one-piece rectangular or block-shaped sensors. Slot-style sensors allow the object being sensed to pass through a sensing slot. With ring-shaped devices, the object passes through the ring's center.

Specifications and Features

Hall effect sensors can be described by a number of specifications and features.

Operating distance range is the maximum range over which the device can provide sensible readings.

The devices may be powered by DC or AC voltage

Devices can tolerate certain temperature ranges (e.g., -13 to 158ºF).

Hall effect position sensors require signal conditioning to make the output usable for most applications. Typically, the signal-conditioning electronics include amplifier stage and temperature compensation (ignore fluctuating ambient temperatures).

Sensors can be weld field immune (will not false-trigger in the presence of extreme electromagnetic fields produced by resistance welders), short-circuit protected, shielded (embedded in metal and no side-sensitive), and/or intrinsically safe (incapable of releasing sufficient electrical or thermal energy to cause ignition of hazardous atmospheric mixtures).

Applications

Hall effect devices are immune to most environmental disturbances that may affect optical or mechanical devices, such as vibration, moisture, dirt or oil films, ambient lighting, etc. They are used in valve position, level detection, process control, machine control, and security.

Magnetic proximity sensors include devices that work on inductive, variable reluctance, magneto resistive or Hall effect principles. Proximity sensors detect the presence or absence of an object using a critical distance.

Magnetic speed sensors rely on a magnet as the sensing element or sensed target to capture rotational or linear speed. They are typically used as gear tooth speed sensors or incorporated into stroboscopes or tachometers.

Variable reluctance linear position sensors and switches are non-contact devices that use variable reluctance based technology, and whose output signal represents the distance between an object and a reference point.